There are various types of oscillator circuits. Depending on the field of application, an oscillator may be required to have certain operational parameters, such as low power consumption, low phase noise, high oscillation frequency, wide oscillation frequency adjustment range, low sensitivity to interference signals and/or low manufacturing cost. By way of example, some LC oscillators, which include frequency determining components such as inductors and capacitors, achieve a number of the above-listed parameters.
An LC oscillator circuit whose oscillation frequency can be adjusted by application of a tuning voltage may be referred to as a voltage controlled oscillator (VCO). One possible way to control the frequency of such an LC oscillator is to use one or more so-called varactors. Varactors include capacitive components that may be tuned by way of an applied voltage. Varying the capacitance value of the capacitive components determines the oscillation frequency of the LC oscillator.